Telephone-exchange system



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L. POLINKOWSKY ET AL TELEPHONE EXCHANGE SYSTEM Filed June l4 1919 8 Sheets-Sheet 8 13.46.910.115. 1e. II

Patented .Fe 5, 192% LIPA POLINKOWSKY, OF NEW YORK, N. iii,

insane AND WILLIAM H. MATTHIE$, 03F HACKER!- SACK, NEW JERSEY, ASSIGNORS T0 WESTERN ELECTRIC COMPANY, INCORPQRATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed June 14,

To all whom it may concern:

Be it known that we, LIPA POLINKOWSKY, a citizen of Russia, and WILLIAM H. MAT- THIES, a citizen of the United States, residing at New York, in the count of New York and State of New York, an at Hackensack, in the county of Bergen and State of New Jersey, respectively, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exactdescription.

This invention relates to telephone exchange systems in which machine switching apparatus is utilized for establishing connections between subscribers lines.

More particularly it relates to a telephone system involving a plurality of, switching stations or exchanges provided with interconnecting trunk lines, whereby subscribers whose lines terminate in one switching .station may obtain connections with other lines local thereto, or by means of said interconnecting trunks may extend a connection to a distant exchange or switching station and thence to a desired line therein.

The object of the invention is the provision, in a system of this character where the designation of a called line is registered on a controlling mechanism at one switching station to control the automatic switches therein, of means whereby the registration of such designation is automatically transferred from saidcontrolling mechanism to a distant switching station and there reproduced on a corresponding controlling mechanism to control the automatic switches in the distant switching station.

A feature of the invention is the provision of means whereby the controlling mechanism in one switching station is able to discriminate between local calls and outgoing calls to a distant station such that when the number of a line belonging to a distant station is registered a transfer device becomes efiectiveto transfer the designation registered to the controlling mechanism in the distant switching station.

Another feature of the invention consists in the provision of a transfer device so arranged as to become automatically associated in succession with the several registers of the set comprising a, register controlling mechanism to transfer the numerical desig- 1919. Serial lilo. 304,212.

- nation registered on such mechanism to the corresponding registers of the register mechanism in a distant switching station.

A further feature of the invention, in a system where the controlling registers are adapted to be advanced to positions corresponding to the complements of the digits of the desired number, consists in the provislon of means, which operates simultaneously with the restoration to normal of said registers, for advancing the corresponding registers of the register mechanism in a distant station to positions corresponding to the complements of said digits.

A still further feature consists in providing means whereby the automatic switches which are controlled in their selective movements by controlling registers are, dependent upon the positions ssumed by said registers, advanced automatically in a selective operation independent of the control of the registers.

These and other features of the present invention will become more apparent as the description progresses.

Referring to the drawings, Fig. 1 shows a subscribers line terminating in the multiple contacts of first line finder switches in a switching station or satellite and the operating circuits of one of these finder switches.

Fig. 2 shows one of a plurality of second line finder switches in the satellite, in the multiple terminals of which appear the connecting circuits leading from the first line finder switches. There is also shown in this figure, a first group selector of the satellite, together with means for associating an idle register controlling mechanism with the circults individual to the second line finder and group selector.

Figs. 3 and 4: illustrate a set of controlling registers with the operating circuits therefor located at the satellite for controlling the movement of the selector switches.

Fig. 5, shows a final selector switch at the satellite and one of the subscribers lines to which the-switch has access as a called line.

Fig. 6, shows the incoming end of a trunk line leading from the firstgroup selector of the satellite to a distant exchange, and the circuits of a first group selector in which said trunk terminates in the exchange, to-

gether with diagrammatic illustration of a second roup selector, and a final selector switch. This figure further shows means for associating an idle register controlling mechanism with the circuits of the first group selector in the exchange.

Figs. 7 and 8 illustrate a register controlling equipment at the exchange, similar in many respects to the register set at the satellite, which serves to control the selective operation of the successive selector switches to establish a connection to a called subscribers line in the exchange.

In considering the circuits and apparatus for settin up a connection between two subscriber s lines in the satellite in connection with the following description, the drawings should be arranged as follows:

Figs. 1, 2 and 5 taken in order from left to right with Figs. 3 and 4 placed below Figure 2. In considering the establishment of a call from the satellite to a distant exchange in connection with the following description, Fig. 6 should be substituted for Fig. 5, and Figs. 7 and 8 placed below Fi 6.

Fri the system disclosed, where exchanges and satellites to the exchanges are involved with trunking facilities whereby a subscriber of the satellite is enabled to obtain telephone connections with subscribers lines belonging to the exchange, provision is also made at the satellites such that a subscriber thereto may obtain connections directly to the lines of other subscribers local to his own satellite without the necessity of first extending the connection over a trunk to the exchange or of utilizing any of the exchange apparatus. Since the capacity of the satellite is relatively small as compared with that of the exchange, the number of selective operations for setting up a connection between two subscribers lines belonging to the exchange is greater than the num ber of selective operations neccessary to establish a connection between two lines helonging to the satellite. Furthermore, the number of selective operations for setting up a connection from a subscribers line local to a satellite over a trunk line to the exchange, and thence to a called subscribers line in theexchange, is greater than the number of operations involved in the establishment of a connection between two lines local to the satellite. The present exchange system has a capacity of 20,000 lines, but could readily be adapted to accommodate any desirable number of lines up to 100,000 with the switch controlling mechanism shown by utilizing all levels of the group selector switches. Accordingly the register controlling mechanism shown in Figs. 7 and 8 at the exchange, comprises five registers for controlling the selecting operations of the first, second, and final selector switches in operations are required for completing a connection between two lines belonging to the satellite. For this purpose, so far as the register controlling mechanism of the satellite switches is concerned, only three registers need be rovided, one for controlling the group se ector of Fig. 2, and the other two for controlling the tens and units selective movements of the final selector switch in Fig. 5. However, it is desirable that no distinction be made between the numbering of a subscribers line to a satellite and a subscribers line to the exchange. That is to say, it is desirable that the numbers of the satellite subscribers lines, listed in the telephone directory, contain as many digital places as the numbers of the exchange lines. By such a provision a universal form of service is given to all subscribers lines in the system, whereby subscribers to the satellite are not concerned as to whether or not a called line belongs to a satellite or to a distant exchange, and in fact, have no way of knowing from its designation in the directory.

To accomplish the foregoing purpose, the register controlling mechanism at the satellite is provided with five registers the same as the register set at the exchange, in order that a registeration may be made of each of the five impulse series transmitted to the satellite corresponding to the number of any line in the system regardless of whether it be a satellite or an exchange line. If the number set up on the satellite registers is one which designates a line belonging to the satellite, the register mechanism is so arranged that only the last three registers are effective to control the satellite switches. If the number set up on the satellite registers is one belonging to a line of a distant exchange, discrimination of'this fact is made by the satellite register mechanism, whereby means are rendered effective to automatically advance the group selector of the satellite into connection with a trunk line outgoing to the exchange without disturbing the positioned registers. Thetrunk linehaving been seized in this manner, a special transfer mechanism is automatically associated, first with the first register in the satellite and operates to transfer the setting of such register to the corresponding register of the exchange register mechanism. Thus the register at the exchange which advances controls the group selector in accordance with the first digit of a called number 1s set up to a position by said transfer mechanism corresponding to the position to which the first register of the satellite was ad vanced by the first digital series of impulses sent by a calling subscriber in the satellite. Thereupon the transfer mechanism is automatically associated with each of the succeeding registers at the satellite to transfer their respective settings to the corresponding registers in the exchange. When the registers at the exchange have all been set, they become operative in the usual manner to control the selective operations of the exchange switches to complete the connection to the desired line.

The register mechanism shown in the present system is of the type in which sequence switches are provided, one for the registration of each digit. Each sequence switch has ten pOSltlOIlS and to a position corresponding to the number of impulses sent from the subscribers dial during the setting period of the registers, and later runs through the remaining positions of its cycle to control the operation of the selector switches. It is therefore obvious that the number of steps taken by a register while controlling a selcctive switch is the complement of the number of impulses sent by the calling subscriber. In order that the switches be controlled in accordance with the numerical designations of the called numbers it only becomes necessary to arrange the calling subscribers dial such that the complement rather than the actual digit itself be sent to the register. The subscribers dial is further designed so that the last interruption of the line in each series of impulses is of comparatively longer duration than the interruptions of the preceeding impulses of the series. The reason for this will become apparent hereinafter.

It is believed that a more thorough understanding is to be had of this invention from a description of the operation of the system in which it is embodied in the establishing of a call from one .subscribers line to another. First, it will be assumed that a subscriber to the line 240 of the satellite desires to obtain a connection with another line local to his own satellite such as the line 440. On removing his receiver from the switchhook to initiate the call, a circuit is established from battery through the left-hand winding of line relay 201, contact and outer armature of cut-off relay 207 over the loop of the line and returning by way of the inner armature and contact of relay 207 through the ri hthand winding of relay 201 to ground. elay 201 attracting its armature closes a circuit from battery, through the inner windings of the common startiiig relays 20 a, armature and contact of relay 201 to place a selectable potential upon the multiple terminals 210 of all the first line finder switches having access to the group in which the calling line appears.

Relays 204 b close a circuit from ground over the armatures and contacts and in parallel through the windings of the power magnets 211, back contacts and armatures of relay 212, back .contacts and armatures of relays 213 of all idle first line finder switches. These switches rotate their brush carriages in the wellknown manner to advance brushes 260, 261, 262 and 263 over the multiple terminals 210, 238, 26 1 and 265 in search of the calling line. As soon as a finder switch moves its test brush 260 into engagement with the test terminal 210 of the calling line, the selectable potential is found thereon and a circuit is closed over the brush 260, through the right-hand high resistance winding of test relay 21 1 to ground. Relay 21 1 attracts its armature and closes a circuit through its left-hand low resistance winding and the winding of the second test rela 212. This circuit being in shunt of the right-hand winding of relay 214 reduces the potential on multiple terminals 210 to render a calling line non-selectable Relay 212 energizes when the brushes are accurately centered. on the terminals of the calling line and opens the power circuit, thereby bringing the brush carriage to rest. A circuit is now completed from battery through armature and contact of relay 213, armature and front contact of relay 212, to place a selectable potential upon the multiple terminals 242 of the second line finder switches such as the one shown in Fig. 2. In parallel with this a circuit is established through the winding of holding magnet 215, through the windings of the common starting relays 216 to ground. Relays 216 energize and complete a circuit from ground over their armatures and contacts, contact 216 (1) of the sequence switch 220 associated with the circuits of the second line finder and firstgroup selector shown in Fig. 2, through the winding of relay 222 to battery and ground. Relay 222, energizing, closes a circuit for the power magnet 221 from ground, armature and back contact of relay 231, armature and front contact of relay 222, armature and back contact of relay 232 through the winding of the power magnet 221, sequence-switch contact 229 (1) to battery and ground. The power magnet 221 operates to rotate the brush carriage carrying the brushes 230, 233, 243 and 244 over the terminals of the connecting circuits leading from the first linefinder switches. When the test brush 230 engages the test terminal 242 of the calling connecting circuit, a circuit is closed from attracting their armatures Add battery over armature and contact of relay 213, as above traced, to the terminal 242 and thence over the test brush 230, contact 228 (1) through the right-hand high resistance winding of test relay 234, back contact and lower armature of relay 224, contact 245 (1) contact 281 of sequence switch 280 to ground. Relay 234 energizes and closes a circuit through its left-hand low resistance winding, its contact and armature through the winding of the second test relay 232 parallel to the circuit above traced through the right-hand winding of relay 234. This circuit, being of comparatively low resistance, reduces the potential of the test terminals 242 to prevent another second line finder from seizing the calling connecting circuit. Relay 232, by attracting its armature, opens the circuit of the power magnet 221 to arrest a movement of the brush carriage with the brushes in engagement with the proper set of terminals. A circuit is also established from battery through the winding of sequence switch 220, contact 217 (1) front contact and armature of relay 232, front contact and armature of relay 222, back contact and armature of relay 231 to ground. Sequence switch 220 energizes in this circuit" and moves from position 1, into position 4.

In position 3, and in the succeeding positions up to position 13 of sequence switch 220, a circuit is closed from battery, through the winding of the cut-off relay 207, terminal 238, brush 261, winding of relay 213, brush 233 through the winding of relay 235, back contact and upper armature of relay 224, contact 226 to ground. The cut-off relay 207 opens the circuit of line relay 201, which in turn permits relays 204 to be deenergized to arrest the movement of the remaining rotating first line finders. Relay 213 energizing in series with the cut-ofi relay 207. and relay 212 by deenergizing, open the circuit of the common starting relays 216. The relay 235 which also energizes in series with relays 207 and 213, closes the circuit of the calling line through to the sequence switch contacts 236 and 2539). Sequence switch 220 being in position 3, at this instant, a bridge is placed across the calling subscribers line, through relay 23], contact 236 (2) to (4), contact and armature of relay 235 over the loop of the line, upper armature and contact of relay 235, contact 239 (2) to (4), through the retardation coil 237 to ground. Relay 231 energizes in this circuit. As sequence switch 220 left position 2, it opened its contact 216 to permit the release of relay 222 and later on leaving position 3, it opened at its contact 228, the circuit of relays 234 and 232, which thereby deenergized. The release of relay 222 is without effect at this time.

selection of an idle one of the register controlling mechanisms takes place. For this.

purpose a testing sequence switch 280 is provided to test the idle or busy condition of the register mechanisms, and upon finding an idle one associates the same with the connecting circuits shown in Fig. 2. The circuit for initiating the testing operation of sequence switch 280 extends from battery through windin of sequence switch 280, contact 225 (4), l ack contact and armature of relay 232, contact 245 (4) contact 281 of sequence switch 280, closed in the successive positions from 1 to 9, to ground. The circuits of the register mechanisms, such as the one shown in Figs. 3 and 4, are multiplied to corresponding contacts as contacts 282, 283 and 284 of a plurality of testing sequences switches 280. The circuits of the register mechanism shown in the drawings are associated with the connecting circuits of the second line finder and group selector when sequence switch 280 is in either position 1 or position 7. It, therefore, the register mechanism shown is idle when the sequence switch 280 reaches either position 1 or 7, a circuit is completed from battery through the left-hand winding of relay 323, contact 322 (1) of sequence switch 320, conductor 293, contact 282 of sequence switch 280, contact 219 (4) through the right-hand winding of relay 234, contact 281 of sequence switch 280, closed in its successive half positions, to ground. The contacts 282 of sequence switch 280 are arranged so that their circuit-closing positions extend over an angular distance sufficient to insure the closure of the above traced test circuit when contact 281 is in one of its half positions. Relay 234 energizes and closes a low resistance circuit through its left-hand winding. contact and armature and through the winding of'relay 232 to ground. The low resistance of this circuit reduces the potential on the conductor 293 to prevent another sequence switch 280 from seizing the selected register mechanism. Relay 232 energizes and opens the circuit of sequence switch 280 which comes to rest. Relay 232 also closes a circuit from battery through the winding of sequence switch 220, contact 217 (4), front contact and armature of relay 232, contact 245 (4), contact 281. standing in either position 1 or position 7 to ground. Sequence switch 220 leaves position 4 and moves into position 5. When sequence switch 220 passes out of position 4 and into position 5 it opens at its contacts 236 and 239 the bridge across the calling line through relay 231 and retardation coil 237, permitting relay 231 to be deenergized. T e calling line is now extended over contacts 236 and 239 to the stepping relay 325 of the llll selected register mechanism for the transmission of impulses to register the designation of the called line. The impulse circuit including stepping relay 325 may be traced from battery through the left-hand winding of such relay, left-hand armature and contact of relay 301, contact 236 (5) contact and lower armature of relay 235, brush 243 brush 262, terminal 264, overthe loop 0 the calling line, terminal 265, brush 263 brush 244, upper armature and contact of relay 235, sequence switch contact 239 (5) right-hand armature and contact of relay 301, through the right-hand winding of the stegping relay 325 to ground.

t the time the register mechanism was selected, the relay 323 was energized in series with relay 234. A circuit was thereupon closed from ground over the armature and front contact of relay 323, right-hand winding thereof, through the winding of sequence switch 320 to battery and ground. Sequence switch 320 moved out of position 1. In leavin position 2, sequence switch 320 opened t e original energizing circuit of relay 323 at its contact 322 permitting said relay to deenergize before sequence switch 320 reached position 3. Sequence switch 320 therefore comes to rest in position 3, and at its contact 332, closes the circuit from the interrupter 333'to the promary winding of a dialling tone coil 324. As relay 323 retracted its armature, a circuit was closed from battery, contact 327 (3) through the Winding of relay 326, back contact and armature of relay 323 to ground, causing the energization of relay 326. When, therefore, stepping relay 325 becomes energized in series with the calling line, a circuit is closed from ground, armature and front contact of relay 325, armature and front contact of relay 326, contact 330 (3), through the right-hand winding of difierential relay 329, armature. and contact of such relay, contact 328 (3), through the winding of the tens thousand register 100 to battery and ground. A parallel circuit to the one just traced is also completed from battery through the coil 331, left-hand winding of differential relay 329, and thence to ground at the armature and front contact of relay 325. Relay 329, being differential, does not attract its armature when both of its windings are energized. The register 100, however, is energized and moves out of position 0. Between positions 0 and 1 of register 100, a direct circuit to ground is closed in the wellknown manner by its local contact 101, thus shunting the right-hand winding of the differential relay 329. This relay now attracts its armature, and register 100, under the control of its local contact, advances into position 1. Relay 337 also energizes in a circuit over contact 328 (3) to ground at the local contact of register 100. Relay 337 remains energized over the circuit traced to ground at the local contact 101 of the register 100, until such register reaches position 1, and in so doing maintains the energization of relay 329 in a circuit to ground at the armature and contact of relay 337. This arrangement insures that the relay 329 cannot become deenergized until sequence switch 100 has advanced through a full position.

The calling subscriber on hearing the distinctive dialling tone in his receiver when sequence switch 320 moves from position 1 to position 3, knows that he may proceed with the manipulation of his dial. Upon the first interruption of the calling line at the subscribers dial, relay 325 retracts its armature and opens the circuit of the lefthand Winding of relay 329 which becomes deenergized. As the line circuit again closes, register 100 is energized once more and moves out of position 1, relay 329 again energizes, the register passes to position 2, and at the next interruption of the line circuit, relay 329 becomes deenergized. This procedure continues, the register advancing one position for each interruption of the line until the first series of impulses has been completed. At each retraction of the armature of relay 325, a momentary circuit is completed over contact 342 and the back contact and armature of relay 325 for relay 334. This relay, however, being slowto-energize does not attract its armature. At the last interruption of the line circuit which, as has been noted, is comparatively longer than the preceding interruptions of the series, the circuit of relay 334 is closed sufiiciently long to permit it to energize. A circuit is now completed from battery, through the left-hand windin of relay 323 to ground at the contact an armature of relay 334. Relay 323 energizes and closes a circuit to drive sequence switch 320 out of position 3. Before sequence switch 320 can reach position 5 to again close contact 342, the line circuit is closed at the subscribers dial and relay 334 deenergizes to in turn permit the deenergization of relay 323 whereby sequence switch 320 comes to rest in position 5. Relay 326, which had its circuit opened at the back contact of relay 323, deenergized while sequence switch 320 was passing from position 3 to position 5. In passing through position 4, the register 100 is energized in a circuit from battery, through the winding of this register, contact 328 (4), contact and armature and right-hand winding of relay 329 to ground at contact 330 (4.). The register 100. advances one step in addition to the position to which it was set by the subscribers sender.

The control of the stepping relay 325 is now shifted from the tens thousand register contact into position 1.

is closed over the left-hand winding of re lay 329 to prevent this relay from attracting its armature. The register 110 moves out of position 0 where it short-circuits the right-hand winding of the differential relay 329 to permit the energization of this relay. When the subscriber operates his dial to send the second series of impulses, the first interruption of the line circuit causes the release of relay 325 which in turn permits the energization of relay 329. The register 110 advances under the control of its local' For each succeeding interruption of the line circuit, register 110 moves forward one position and at the last interruption of the impulse series, relay 334 energizes to cause the operation of relay 323 which closes a circuit at its armature and front contact to drive the sequence switch 320 out of position 5. As sequence switch 320 moves from position 5 to position 8, the line circuit is again closed to cause the energization of relay 325 and the consequent deenergization of relays 334 and 323 so that sequence switch 320 will stop when it reaches position 8.- Relay 326 deenergizes as sequence switch 320 leaves position 5, and again energizes when said sequence switch stops in position 8, similar to the manner described in connection with the setting of the first register. As relay 326 is again energized, a circuit is completed from ground, armature and front contact of relay 325, armature and front contact of relay 326, contact 105 of register 100, right-hand winding and armature and contact of relay 329, sequence switch contact 335 (8), through the winding of .the hundreds register 120 to battery and ground.

The calling subscriber, manipulatin his dial in accordance with the third digit of the desired number causes the register 120 to be advanced to its proper position under the control of the stepping relay 325. At the termination of the third series of impulses relay 334 is energized, causing the energization of relay 323 to close the circuit for sequence switch 320 which moves from position 8 into position 10. A circuit is thereupon completed from ground, armature and front contact of relay 325, armature and front contact of relay 326, contact 105, righthand winding'and armature and contact of relay 329, sequence switch contact 335 (10), through the winding of the tens register 130 to battery and ground. The interruption of the line circuit during the sending of the fourth series of impulses causes the advance of register 130 under the control of the stepping relay 325. At the end of this series, sequence switch 320 is energized in'the manner already described, and moves from position 10 into position 12. A circuit for the control of the units register 140 is completed from ground, armature and front contact of relay 325, armature and front contact of relay 326, contact 105, right-hand winding and armature and contact of relay 329, sequence switch contact 336 (12), through the winding of the units register 140, battery and ground. As the calling subscriber operates his dial in accordance with the final digit, the stepping relay 325 operates as above described to control the positioning of the register 140. The last interruption of the line being of a comparatively long duration, relay 334: is energized and sequence switch 320 is driven from position 12 into position 14.

After the first three series of impulses have been sent from the calling subscrihers station and, correspondingly, the first three registers advanced to their set positions, group selection is proceeded with without waiting for the tens and units registers to be set. The first three registers 100, 110 and 120 and their associated circuits are capable of discriminating whether" the number that is being registered is that of a line local to the satellite or an exchange line.

As hereinbefore stated, the capacity of the exchange system is 20,000 lines. These lines are numbered from 10,000 to 29,999, whereby the tens thousand register 100 is only utilized in two of its positions. When the first digit of a called number is 1, which indicates that the called line belongs to the first tens thousand group, register 100 is advanced under the control of the calling dial to its ninth position, the complement of the desired digit, and thereafter automatically advanced into its zero position as already described. If the first digit of the called number is 2, which indicates that such'line belongs to the second tens thousand group, the rcgister 100 is first advanced to the complementary position 8 and thereafter moved an additional step into its 9th position. Hence the contact 105 of the register 100 will always be closed in either the 9th or zero position of the tens thousand register.

The numbers of the subscribers lines belonging to the satellite, of which it has been noted there are 400 in the present system, are assigned to the second group of 10,000 lines. Furthermore these satellite lines are assigned to the second thousand in the second ten thousand, which corresponds to the 8th position of register 110, and comprise the 8th, 7th, 6th and 5th groups of lines in the second thousand which correspond to the 2nd, 3rd, 4th and 5th positions of register 120. Therefore when a call is made to a line belonging to the satellite, the register 100 is set to its 9th position, the register to its 8th position, and the hundredsregister in either its 2nd, 3rd, 4th or 5th position.

The first three registers having been set, the sequence switch 320, it will be recalled, thereupon moves from position 8 to position 10. A circuit is then closed for the sequence switch 350, which controls the restoration to the positioned registers during the selective movements of the switches. This circuit may be traced from battery through the winding of sequence switch magnet 350, contact 352 (1), contact 103, contact 338 to ground. Sequence switch 350 leaves position 1. In position 11} of sequence switch 350, a circuit is closed from battery through the windings of relays'382 and 383, contact 106 or register 100, contact 116 of register 110, contact 127 of register 120, to ground at contact 372. Relays 382 and 383 energize and lock up in a circuit from battery through the windings of these relays, front contact and left-hand armature of relay 383 to ground at contact 369. Sequence switch 350 continues to move over positions 2, 3, and 4 and comes to rest in position 5 bymeans of a circuit closed from battery, through the winding of such sequence switch, lefi-hand armature and contact of relay 382. Sequence switch contact 380, closed in positions 2 to 4, front contact and right-hand armature of relay 382 to ground. At the same time relay 357 is energized in a circuit from battery, through its winding, sequence switch contact 380, to ground at the right-hand armature of relay 382. Relay 357 serves to maintain the fundamental circuit open while sequence switch 350 is passing to position 5.

s sequence switch 350 moves into position 2, the relay 359, which controls the restoration of the registers, is energized over its right-hand winding, contact and armature of relay 355, sequence switch contact 35 1, contact 152 of sequence switch to ground. Relay 359, by attracting its armature, insures that the registers remains undisturbed until the fundamental circuit is in condition to control the group selector.

In position 5 of sequence switch 350, the relay 357 deenergizes and the fundamental circuit is completed from battery through the winding of relay 222, contact 247 (5) of sequence switch 220, conductor 296, armature and contact of relay 357 through the winding of the stepping relay 355, contact tion 5 and into position 6 where a circuit is closed for the trip spindle power magnet 24:8. Thls circuit may be traced from battery through the winding of magnet 248, contact 227 (6), front contact and armature of relay 222, back contact and armature of relay 231 to ground.

The trip spindle rotates in the well-known manner causing a short circuit of the stepping relay 355 in the fundamental circuit for each brush tripping position. When the relay 355 is first deenergized as a result of the short circuit produced by interrupter 250, a circuit is established from battery through the winding of the register 120 contact 122, contact 366 (5), contact and armature and left-hand winding of the relay 359, contact and armature of relay 355, contact 354 and contact 152 to ground. In parallel thereto a circuit is also closed through the righthand winding of relay 359 to ground at the contact 152.

The relay 359 being differential, does not attract its armature when both windings are energized. The register 120 however, is energized and moves out of the position to which it was set from the calling subscribers dial. As soon as the local contact 121 is closed between positions, a direct circuit is afi orde'd to ground, thus shortcircuiting the left-hand winding of the differential relay 359, permitting this relay to become energized. The register 120 con tinues to move under the control of its local contact into the next position.

During the time that the register 120 is advancing from one position to the next, relay 362 is energized in a circuit from battery through the winding thereof, contact 366 (5), contact 122 to ground at the local i contact 121. Relay 362 closes a substitute circuit from battery through the right-hand winding of relay 359 to ground at the contact 153 of sequence switch 150, to maintain the energization of relay 359 until the register 120 fully advances to its next position. As the brush tripping spindle reaches its first tripping position, the short circuit is removed on contact 250 and relay 355 once more energizes. The register 120 having advanced to a full position, the local contact 121 is opened and relay 362 becomes deenergized. Both of the above circuits for.

the right-hand winding of relay 359 being open, said relay releases its armature. Regbattery, through the winding of sequence switch magnet 350, left-hand armature and contact of relay 382, contact 364 (5), contact 124 (0), contact 366 5), contact and armature and left-hand winding of relay 359, contact and armature of relay 355 to ground at contact 152. In parallel to the circuit above described, a circuit is also completed for relay- 357. Sequence switch 350 moves from position 5 into position 6 while relay 357 energizes to maintain the fundamental circuit open. -After the interrupter contact 250 is opened, relay 222 deenergizes and closes a circuit from battery, through the winding of sequence switch 220, contact 251 (6), back contact and armature of relay 231 to ground, to drive sequence switch 220. out of position 6 and into position 7. The relay 222 is now energized in a circuit from battery through the winding of said relay, contact 219 (7), conductor 293, back contact and armature of relay 339, contact 340 of sequence switch 320 to ground.

In position 7 of sequence switch 220 the power magnet 241 is energized by means of the circuit completed from battery, through the winding of this magnet, contact 223 (7), back contact and armature of relay 232, front contact and armature of relay 222 to ground at the back contact and armature of relay 231. The power magnet 241 operates to rotate the group selector brush carriage, advancing its brushes over the terminals of the selected level of trunks. In reaching the test terminal of an idle trunk a selectable potential is found thereon and a circuit closed from battery 442 at the final selector shown in Figure 5, contact 441 (1) of sequence switch 450, terminal 266, brush 252, contact 228 (7) through the right-hand high resistance winding of test relay 234, back contact and lower armature of relay 224, contact 245 (7), contact 281 to ground. The relay 234 energizes in this circuit and closes a low resistance path to ground through its left-hand winding, contact and armature, and the winding of relay 232 in parallel with the circuit through its righthand high resistance winding. This low resistance circuit reduces the potential on test terminals 266 to render the selected trunk busy to other group selector switches. Belay 232 also energizes to establish a circuit from battery, through the winding of sequence switch 220, contact 217 (7 front contact and armature of relay 232, front contact and armature of relay 222 to ground at the armature of relay 231. The sequence switch 220 moves over position 8 and 'into tion 9, is held open at the register mechanism until sequence switch 350 moves into position 7, which only takes place after the tens and units registers 130 and 140 have been positioned from the calling subscribers substation. After the units register has been set, it will be recalled, sequence switch 320 advances into position 14. In this position a circuit is completed from battery through the winding of sequence switch 350, contact 352 (6), contact 341 (14), to advance sequence switch 350 out of position 6 and into position 7. The fundamental circuit is now completed for the final selector and ma be traced from battery through the win ing of relay 452 contact 459 (1) of sequence switch 450, brush 267, contact 247 (9) conductor 296, armature and contact of relay 357, through the winding of steppin relay 355, contact 356 7 front contact an righthand armature of relay 383, conductor 297,

contact 255 (9), brush 268, contact 458 (1) to ground. Both relays 355 and 452 ener gize in the above traced circuit. Relay 452 closes a circuit from battery through the winding of sequence switch magnet 450 contact 451 (1) to ground at the front contact and armature of relay 452 to drive sequence switch 450 out of position 1 and into position 2.

The power magnet 448 of the tripping spindle is then energized in a circuit traceable from battery through the winding of said magnet, contact 466 (2), front contact and armature of relay 452 to ground. The tens register 130 is now restored to its normal position to control the tens selection of the final selector in a manner similar to the restoration of the hundreds register 120. The circuit for energizing the register 130 may be traced from battery through the winding of the said register, contact 132, contact 366 (7 contact and armature and left-hand winding of relay 359, contact and armature of relay 355 to ground at the contact 152. In parallel therewith the relay 357 is also energized to open the fundamental circuit as above described. Sequence switch 350 thereupon advances into position 9.

When the interrupter contact 455 is opened after register 130 reaches position zero, relay 452 becomes deenergized since the fundamental circuit is now open at the register mechanism. Sequence switch 450 moves into position 5 by means of a circuit including the contact 445 and the back contact and armature of relay 452. Sequence switch 350 leaving position 7, opens the circuit of relay 357 at contact 366 so that the fundamental circuit is again completed at the register mechanism in position 9 of sequence switch 350 prior to the time that se quence switch 450 of the final selector reaches position 5. Relays 452 and 355 are again energized, and a circuit is completed thereby for the power magnet 461, traceable from battery through the winding of said magnet, contact 446 (5) to ground at th front contact and armature of relay 452. The brush carriage of the said selector is rotated in the usual manner to trail brushes 470, 471 and 473 over the terminals of the tens level determined by the osition of the brush tri ping spindle. or each set of termina s passed over by the selected set of brushes, a short circuit is placed around the stepping relay 355 in the fundamental circuit by the interrupter contact 457. Relay 452 remains energized during the closures of the contact 457 and relay 355 intermittently retracts and attracts its armature due to the short circuit closed from battery through the winding of relay 452, contact 453 (5), and interrupter contact 457. During this operation the units register 140 is returned to its normal position in a circuit from battery through the winding of said register, contact 142, contact 367 (9), contact and armature and left-hand winding of relay 359, contact and armature of rela 355 to ground at contact 152. When register 140 reaches position 0, which corresponds to the brushes of the final selector, having been advanced to the proper set of terminals, and as soon thereafter as relay 355 retracts its armature a circuit is closed from battery, through the winding of sequence switch 350, left-hand armature and contact of relay 382, contact 364 (9), contact 144 (0), back contact and armature of relay 374, contact 143 (0), contact 367 (9), contact and armature and left-hand winding of relay 359, to ground at contact 152. Sequence switch 350 moves out of position 9 and into position 12.

In position 10 of sequence switch 350 relay 339 is energized in a circuit from battery, through the winding of said relay, contact 368 (10), front contact and left-hand armature of relay 383, to ground at contact 369. Relay 339 energizes and opens the circuit hereinbefore traced for relay 222. Relay 222 deenergizing, closes a circuit from battery through sequence switch winding 220, contact 251 (9), back contact and armature of relay 222, back contact andarmature of relay 231 to ground, to drive sequence switch 220 into position 10. In this position a circuit is closed at the back contact and armature of relay 262 including contact 258 (19), to drive sequence switch 220 out of position 10 and into position 11. 011 leaving position 9, se uence switch 220 disconnects the calling su cribers line from the register mechanism at its contacts 239 and 236, and connects said line in series with the supervisory relay 231 and retardation coil 237. The register set now being disconnected from the calling subscribers line stepping relay 325 releases its armature to close a circuit from ground, armature and back contact of relay 325, contact 348 14), through the winding of sequence sWitc magnet 320 to battery, to drive said sequence switch out of position 14 into position 15. A circuit is then closed from battery through the winding of sequenc switch 356 contact 367 (12), to ground at contact 343 (15), whereby sequence switch 350 moves into position 13.

I The registers 100 and 110 which remained inactive uring the setting up of the switches are now returned to their normal positions. The circuit for energizing register 100 may be traced from battery throu h the Winding of said register, contact 102 59), contact 361 13), to ground at contact 343 (15). When the register 100 reaches position 0, sequence switch 350 is advanced into position 14 in a circuit over contact 379 (13), contact 363 (13), contact 104 (0), contact 361 (13), to

ground at contact 343 (15). In this position the register 110 is restored to normal by means of a circuit from battery, through the winding of said register, contact 112,. contact 361 (14), to ground at contact 343 (15). In position 0 of register 110, a circuit is closed to drive sequence switch 350 into position 15, which circuit leads from battery, through the winding of said sequence switch, contacts 37 9 and 363 (14), contact 114 (9), contact 361 (14), contact 343 (15), to ground. Sequence switch 350 is driven into position 16 in a circuit including contact 379 (15), contact 364 (15) contact 124 of register 120, contact 366 (15), and contact 343 (15). lin position 16 0 sequence switch 350 a circuit is closed to drive the same into position 17, traceable from battery through the winding of said sequence switch, contact 379 (16) contact 364 (16), contact 134 (0) of register 130, contact 366 (16) toground at contact 343 (15). In position 17 a circuit is finally closed to drive sequence switch 350 into position 1, which includes contacts 379 and 364 (17 contact 144 (0) of register 140 back contact and armature of relay 374, contact 143 (0), contact 367 (17), and contact 343 (15). In position 1 a circuit is completed for the energization of relay 323 from battery through the left-hand winding thereof, contact 322 (15) to ground at contact 369 (1). Relay 323 energizes and closes at its armature and front contact a circuit to drive sequence switch 320 out of position 15 and into position 17. A circuit is then closed from battery throu h the windings of relay 334, contact 342 (1 back contact and armature of relay 326, contact 340 (17) to ground. Relay 334 attracts its armature and closes a holding circuit for the left-hand Winding of relay 323 to maintain this relay energized, whereby sequence switch 320 continues to move over position 17 and into position 1. The register controlling equi ment has now been disassociat-ed from t e cord circuit and completely restored to its normal condition, ready to be taken for use in controlling subsequent connections.

As soon as the interrupter contact 457 is opened at the time the brushes of thefinal selector are set upon the proper terminals, relay 452 deenergizes, since, as already seen, the fundamental circuit is open, at this time, at the register mechanism. Sequence switch 450 thereupon advances into position 6 by means of a circuit including contact 445 (5) and the back contact and armature of relay 452. In position 6 relay 452 is again energized in a circuit from battery, through the winding thereof and contact 449 (6) to ground. Sequence switch 450, therefore, continues to move into position 10, a circuit being closed therefor, including contact 451 (6) and the front contact and armature of relay 452.

In passing through position 8 a test is made to determine whether the called line is busy or idle. Assuming it to be idle, a selectable otential will exist on the test terminal 46 and a circuit is closed by way of test brush 470 through the right-hand high resistance winding of test relay 464 to ground at contact 449 (8). Relay 464 energizes and closes a low resistance circuit to ground through its left-hand winding, contact and armature and the winding of relay 462 and contact 475 (9-10). This low re sistance circuit reduces the potential on terminals 467 sufliciently to render the called line non-selectable to other connector switches. Relay 462 attracts its armature and closes a circuit from battery, through the winding of sequence switch 450, contact 445 (10), front contact and armature of relay 462 to ground at the back contact and armature of relay 452, to drive sequence switch 450 over position 11 and into position 12. A ringing current is now immediately applied to the called line from the source 476. A circuit is also established for relay 452, to ground at the interrupter 469 which. when closed causes said relay to energize to complete a circuit to drive sequence switch 450 into position 13. This circuit may be traced from battery, through the winding of said se uence switch, contact 451 to round at the ront contact and armature o 1 relay 452. In position 13 relay 452 is connected to a second interrupter 472 which, when closed, causes relay 452 to energize to drive sequence switch 450 into position 14. The interrupters 469 and 472 are arranged to provide a predetermined interval of time between the closures of the above mentioned circuits so that sequence switch 450 is brought from position 12 into position 14 after the lapse of a definite interval. In position 14 the ringing source 476 is disconnected and ringing current is supplied by means of the ringing machine 474. The circuit for the ringing current may be traced from the ringing machine 474, contact 477 (14), brush 471 over the called line and through the ringer thereof, returning by way of brush 473, contact 478 (14), through the winding of ringing control relay 460 to ground. During the time ringing current is being impressed upon the line, the calling subscrlber is informed of this fact by a characteristic sound produced in his receiver by means of the closure of the primary circuit of tone coil 447 at sequence switch contact 479 (14). When the ca led subscriber answers, relay 460 is energized and closes a circuit over its armature and contact, contact 451 (14) through the winding of sequence switch 450 to battery and ground to drive said sequence switch into position 15. The calling line is now connected directly through to the called line over sequence switch contacts 477 and 478, and relay 262 and retardation coil 257 are included in bridge of the called line. Relay 262 energizes and closes a circuit from its armature and front contact, contact 217 (11), through the winding of the sequence switch 220. to drive said sequence switch into position 12.

When the conversation is completed and the calling subscriber restores his receiver to the switchhook, relay 231 deenergizes and a circuit is completed from ground, over the armature and back contact thereof, armature and back contact of relay 222, contact 251 (12), through the winding of sequence switch 220 to battery. Sequence switch 220 moves out of position 12, over position 13 and into position 17 where a circuit is closed from battery, through the power magnet 241, contact 223 (17), back contact and armature of relay 232, contact 245 (17), and contact 281 to ground. Power magnet 241 operates to restore the brush carriage to its normal position, when the brush carriage reaches its home position, a circuit is closed from battery. contact 229 (17), interrupter brush 269, through the winding of relay 232 to ground. Relay 232 energizes to open the circuit of power magnet 241 whereby the brush carriage ceases to rotate. A circuit is also closed from battery through the insects windin of sequence switch 220, contact 217 (17), front contact and armature of relay 232, contact 245 (17) to ground at contact 281, whereby sequence switch 220 moves from position'17 into position 18.

.The second line finders, as the one shown in Fig. 2 are arranged in pairs so that when both finders of a pair are idle, only one at a time is capable of hunting for a calling circuit. To accomplish this, the circuits are so arranged that when idle, the sequence switch 220 of the finder to be taken for use, S

stands in position 1, whereas the sequence switch of the other finder of the pair stands in position 18. The sequence switch 220 is driven from position 18 into position 1 by means of a circuit closed from battery through the winding of se uence switch 220, contact 217 18), to groun at the front c0ntactand armature of relay 262. Relay 262 is energized in a circuit including contact 256 (18) and contact 270.

When sequence switch 220 leaves position 12, it opens at contact 228, the circuit of relay 443, which was closed at the time the test brush 252 of the group selector was set upon the terminal 266. Relay 443 retracting its armature, closes a circuit including contact 444 to drive sequence switch 450 from position 16 into position 17. If the called subscriber has replaced his receiver to the switchhook, sequence switch 450 moves into position 18 in a circuit including contact 445 (17) and the back contact and armature of relay 452. In position 18 the brush carriage of the final selector is rotated to its normal position by power magnet 461. The circuit for this magnet includes contact 446 (18), back contact and armature of relay 462, and the back contact and armature of relay 452. When the brush carriage is fully restored, a circuit is closed from ground, contact 457 in its home position, sequence switch contact 454 (18), and through the winding of relay 452 to battery. Relay 452 attracts its armature and opens the circuit of power magnet 461 bringing the brush carriage to rest. A circuit is also closed from ground, armature and front contact of relay 452, contact 451 (18), through the winding of sequence switch 450 to battery, to drive said sequence switch into its normal position 1.

Assuming that the called line is busy during the time sequence switch 450 of the final selector is passing through position 8, no selectable potential will be found on the test terminal 467 and consequently the test relays 464 and 462 will not be energized. Sequence switch 450, therefore, comes to restin position 10, in which position a busy tone interrupter 480 is connected in the primary circuit of the tone coil 447 at: scquence switch contact 479. The calling subscriber hearing the busy tone, replaces described.

224, front contact and armature thereof, con-' tact 245 (11), to ground at the contact 281.

12 and 13 into position 17. In position 17, restoration of the group selector takes place in the manner already described.

The connection above described is one in which no translation is required at the final selector switch. That is to say, the hundreds digit of the called number is even and the corresponding line is located in the first or even section of terminals at the final selector. As is well understood in systems of this character, the final switches have a capacity of 200 lines, which are arranged in two groups or sections of 160 lines each. To make connection with the terminals of a called line belonging to an even hundreds groups the brushes are driven over a number of terminals corresponding to the number of the called line; whereas, if connection is desired with a line belonging to an odd hundreds group, it is necessary to provide translation so that the final selector brushes, after having been advanced over a number of terminals corresponding to the number of the called, line, will be made to advance ten additional positions into connection with the proper line in the second or odd section of the selector bank. Assuming that a connection 1S required with a line belonging to an odd hundreds group. it becomes necessary that the hundreds register 120 provide for translation. As sequence switch 350 passes through position 3, a circuit is closed from battery through the windings of re lay 374 and 373, contact 375 (3), contact 126 of the hundreds register, which is closed in all odd positions, front contact and lefthand armature of relay 383. to ground at contact 369. Relays 374 and 373 energize and lock up in a circuit over the contact and armature of relay 373, contact 145, to ground at contact 369. Hundreds and tens selections take When, during units selection, however, the register 140 reaches position 0, no circuit is provided to drive sequence switch 350 out of position 9 as in case betore'described, since relay 374 is energized.

Units register 140, therefore, continues to operate through a complete additional cycle. whereby the brush carriage of the final selector is advanced to the proper set of terminals in the second section of the bank. ()n passing from position 0 to position 1,

equence switch 220 moves over positions place in the manner already the holding circuit of relays 374 and 37 3 is open atcontact 145, permitting these relays to deenergize. Hence, when the register 140 a ain' returns to its zero position the usual circuit is closed to drive sequence switch 350 out of position 9 and into position 12.

The case will now be assumed in which the subscriber at satellite line 240 desires to establish a connection with the line of a subscriber belonging to a distant exchange, as the line 610. The number of the line 610 will be taken for example as 12453.

' registration of the called number. The callmg subscriber thereupon operates his dial in accordance with the digits of the called number, which in effect, results in thetransmission of series of im ulses corresponding to the complements o the digits of such number. That is, in the case assumed nine impulses are sent for the first digit, eight impulses for the second digit, six impulses for the third digit, five impulses for the fourth digit and seven impulses for the fifth digit. In response to these impulses the tens thousand register 100 of the satellite mechanism is advanced to its ninth position under the control of the calling subscribers dial and subsequently automatically moved into its zero position as hereinbefore explained; the thousands register 110 is advanced to its eighth position; the hundreds register 120 is advanced to its sixth position. The tens register 130 to'its fifth position and the units register 140 to its seventh position. It will be observed that the number of the exchange line assumed has for its tens thousand digit the Figure 1, or in other words that this line belongs to'the first tens thousand grou Since the called line is one which belongs to a distant exchange,-it becomes necessary, in accordance with the principles of the present invention, to provide means whereby the numerical designations, which have already been registered at, the controlling equipment in the satellite, may be repro-.

duced at the registering mechanism in the exchange for the purpose of controlling the selective switches therein to set up the desired connection. Accordingly, there is provided a transfer sequence switch 150 which is automatically associable in succession with the'several registers of the set in the fvious that when this register in the exchange becomes effective to control the selective operation of a selector switch, it will operate through a number of ositions in returning to normal, corres ondm to the actual digit of the callednum r. of the registers at the satellite are transferred successively to the corresponding reg isters in the exchange by means of the transfer se uence switch150;

Whi e the number of registers in the satelhte is the same as the number of registers in the exchange, namel five registers, and all of which are required for controlling the operations of the exchange switches in establishing a connection, rovision must be made such that a connection may be made from the satellite over a trunk line to the exchan e without utilizing one of the satellite registers. This is accomplished, as will be hereinafter explained in detail by means operative to automatically. advance the group selector in the satellite into connectlon with a trunk line leading to the exchange.

When the first three registers in the satellite have been' setrfrom the calling subscribers substation, the sequence switch 320 moves into position 10. In this position, the circult hereinbefore traced for relays 382 and 383, which included contact 106 of register 100, contact 116 of register 110 and contact 127 of register 120, in the case of a local call, now remains open since register 100 is standing 1n position 0 and register 120 in pos1t1on 6. The fact that relays 382 and 383 are not energized at this time is what determines that the number being registered is that belonging to an exchange line. A circult, however, is closed for sequence switch 350, traceable from battery to the winding of said sequence switch, contact 352 (1) contact 103 (0), contact 338 (10) to ground. Wh1le sequence 350 is passing from position 1 'to position 2, relay 357 is energized in a circuit from battery throu h the winding thereof, contact 379 (1 to 2 and local contact 351 to ground. -As soon, however, as sequence switch 350 reaches position 2 the local contact 351 is opened, the relay 357 releases its armature and establishes a circuit from battery through the winding of relay 222, Figure 2, contact 247 (5), conductor 11 short, the settings, 

